Torsades de pointes: Difference between revisions
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==Background== | ==Background== | ||
* | *Form of polymorphic [[VTach]] | ||
*Associated with prolonged QT | **Gradual change in the amplitude of QRS complexes and twisting around isoelectric line | ||
*Associated with congenital or acquired [[prolonged QT]] which may be secondary to medications | |||
== | ===Common Causes=== | ||
Increasing HR decreases QT interval | '''POINTES''' mnemonic: | ||
#Magnesium - decreases calcium influx | *[[Phenothiazines|'''P'''henothiazines]] | ||
# | *'''O'''ther medications (ie [[TCAs]]) | ||
# | *[[ICH|'''I'''ntracranial bleed]] | ||
# | *'''N'''o known cause (idiopathic) | ||
#Isoproterenol - Increases HR / AV conduction | *'''T'''ype I [[antiarrhythmics]] ([[quinidine]], [[procainamide]], disopyramide) | ||
# | *[[electrolyte Abnormality|'''E'''lectrolyte abnormalities]] ([[hypokalemia|hypoK]] & [[hypomagnesemia|hypoMg]]) | ||
*'''S'''yndrome of [[Prolonged QT]] (aka Long QT Syndrome) | |||
*Other causes: | |||
**[[Organophosphate toxicity]] | |||
**[[Hydrocarbon toxicity]] | |||
**[[Chloral hydrate toxicity]] | |||
**[[Hypothermia]] | |||
==Clinical Features== | |||
*[[Syncope]] | |||
*[[Dizziness]], lightheadedness | |||
*[[Palpitations]] | |||
*Sudden [[cardiac arrest]] | |||
==Differential Diagnosis== | |||
*Drug induced | |||
*Congenital long QT | |||
*[[Hypocalcemia]] | |||
*[[Hypomagnesemia]] | |||
*[[Hypokalemia]] | |||
*[[Hypothermia]] | |||
*POINTES as above | |||
{{Tachycardia (wide) DDX}} | |||
==Evaluation== | |||
===Workup=== | |||
*[[ECG]] | |||
*BMP, Mg, Phos | |||
===Diagnosis=== | |||
[[File:12leadTorsade.jpg|thumb|Classic torsades in 12-lead]] | |||
[[File:Torsades de Pointes TdP.png|thumb|Torsades de Pointes (TdP) in patient with a potassium of 2.4 mmol/L and a magnesium of 1.6mg/dL.]] | |||
*[[ECG]] showing the QRS complexes “twisting” around the isoelectric line | |||
==Management== | |||
''Increasing HR decreases QT interval'' | |||
#[[Magnesium sulfate]] - decreases calcium influx | |||
#*1-2gm IV over 1-2 min, repeat in 5-15min; then 1-2gm/hr (3-10mg/min) drip | |||
#**Danger of [[hypermagnesemia]] → depressed neuromuscular function and respiratory drive, so monitor closely | |||
#**Supplement with K+ | |||
#[[Isoproterenol]] - Increases HR / AV conduction | |||
#*2-8 mcg/min | |||
#*Target HR > 90 bpm | |||
#[[Overdrive Pacing]] - Atrial > Ventricular pacing | #[[Overdrive Pacing]] - Atrial > Ventricular pacing | ||
# | #*Goal HR 90-120 | ||
#Defibrillation / | #*Note: Not a treatment for TdP, but useful in maintaining sinus rhythm | ||
#[[Defibrillation]] / [[synchronized cardioversion]] - Patient in extremis | |||
#'''AVOID''' amiodarone and procainamide, which may worsen prolonged QT | |||
# [[Lidocaine]] (a class Ib antiarrhythmic drug) shortens the QT interval and may be effective especially for drug-induced torsades de pointes | |||
#*[[Lidocaine]] 1 mg/kg bolus, followed by 0.5-4 mg/min, titrated to rhythm response<ref>Reachi B, Negrelli J, Hickman A, Beesley S, Osborn J (2019) Isoproterenol and Lidocaine for Recurrent Torsades de Pointes in a 32-year-old Pregnant Woman. Int J Crit Care Emerg Med 5:092.</ref> | |||
#*Inpatient may monitor plasma lidocaine levels, with goal < 6 mcg/mL | |||
==Disposition== | |||
*Admit | |||
==See Also== | ==See Also== | ||
*[[Tachycardia (Wide)]] | *[[Tachycardia (Wide)]] | ||
*[[ACLS (2010 Guidelines)]] | *[[ACLS (2010 Guidelines)]] | ||
*[[In-Training Exam Review]] | |||
== | ==References== | ||
<references/> | |||
[[Category: | [[Category:Cardiology]] | ||
Latest revision as of 22:10, 7 September 2022
Background
- Form of polymorphic VTach
- Gradual change in the amplitude of QRS complexes and twisting around isoelectric line
- Associated with congenital or acquired prolonged QT which may be secondary to medications
Common Causes
POINTES mnemonic:
- Phenothiazines
- Other medications (ie TCAs)
- Intracranial bleed
- No known cause (idiopathic)
- Type I antiarrhythmics (quinidine, procainamide, disopyramide)
- Electrolyte abnormalities (hypoK & hypoMg)
- Syndrome of Prolonged QT (aka Long QT Syndrome)
- Other causes:
Clinical Features
- Syncope
- Dizziness, lightheadedness
- Palpitations
- Sudden cardiac arrest
Differential Diagnosis
- Drug induced
- Congenital long QT
- Hypocalcemia
- Hypomagnesemia
- Hypokalemia
- Hypothermia
- POINTES as above
Wide-complex tachycardia
Assume any wide-complex tachycardia is ventricular tachycardia until proven otherwise (it is safer to incorrectly assume a ventricular dysrhythmia than supraventricular tachycardia with abberancy)
- Regular
- Monomorphic ventricular tachycardia
- PSVT with aberrant conduction:
- PSVT with bundle branch block^
- PSVT with accessory pathway
- Atrial flutter with bundle branch block^
- Sinus tachycardia with bundle branch block^
- Accelerated idioventricular rhythm (consider if less than or ~120 bpm)
- Metabolic
- Irregular
- Atrial fibrillation/atrial flutter with variable AV conduction AND bundle branch block^
- Atrial fibrillation/atrial flutter with variable AV conduction AND accessory pathway (e.g. WPW)
- Atrial fibrillation + hyperkalemia
- Polymorphic ventricular tachycardia
^Fixed or rate-related
Evaluation
Workup
- ECG
- BMP, Mg, Phos
Diagnosis
- ECG showing the QRS complexes “twisting” around the isoelectric line
Management
Increasing HR decreases QT interval
- Magnesium sulfate - decreases calcium influx
- 1-2gm IV over 1-2 min, repeat in 5-15min; then 1-2gm/hr (3-10mg/min) drip
- Danger of hypermagnesemia → depressed neuromuscular function and respiratory drive, so monitor closely
- Supplement with K+
- 1-2gm IV over 1-2 min, repeat in 5-15min; then 1-2gm/hr (3-10mg/min) drip
- Isoproterenol - Increases HR / AV conduction
- 2-8 mcg/min
- Target HR > 90 bpm
- Overdrive Pacing - Atrial > Ventricular pacing
- Goal HR 90-120
- Note: Not a treatment for TdP, but useful in maintaining sinus rhythm
- Defibrillation / synchronized cardioversion - Patient in extremis
- AVOID amiodarone and procainamide, which may worsen prolonged QT
- Lidocaine (a class Ib antiarrhythmic drug) shortens the QT interval and may be effective especially for drug-induced torsades de pointes
Disposition
- Admit
See Also
References
- ↑ Reachi B, Negrelli J, Hickman A, Beesley S, Osborn J (2019) Isoproterenol and Lidocaine for Recurrent Torsades de Pointes in a 32-year-old Pregnant Woman. Int J Crit Care Emerg Med 5:092.